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猪繁殖与呼吸综合征研究进展 总被引：2，自引：1，他引：1
猪繁殖与呼吸综合征（Porcine reproductive and respiratory syndrome,PRRS）由猪繁殖与呼吸综合征病毒（PRRSV）引起,以母猪繁殖障碍和仔猪呼吸道综合征为主要特征。PRRSV具有不断变异的能力,毒力更强的新型PRRSV毒株不断出现。2006年我国就出现了美洲型PRRSV变异株,严重危害着我国养猪业。为了更好地认识猪繁殖与呼吸综合征在我国的发生与流行,对PRRS的病原学、流行病学、致病机制、遗传变异、诊断与控制技术等方面的研究进展进行综述。 相似文献
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猪繁殖与呼吸综合征(Porcine Reproductive and Respiratory Syndrome,PRRS)由猪繁殖与呼吸综合征病毒(PRRSV)引起,以母猪繁殖障碍和仔猪呼吸道综合征为主要特征。近几年,由于PRRSV不断变异,毒力更强的新型PRRSV毒株严重危害着养猪业。2006年入夏以来,我国南方一些猪场暴发了一种以高热、高发病率和高死亡率为特征的传染病,运用分子生物学方法诊断与鉴定,最后证实猪繁殖与呼吸综合征病毒变异株为主要病原之一。为更好地防制猪繁殖与呼吸综合征在我国的发生与流行,笔者对PRRSV的病原学、流行病学、致病机制和遗传变异等方面的研究进展进行综述。 相似文献
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为了解2014年和2015年华东部分地区(山东省和福建省)猪繁殖与呼吸综合征病毒(Porcine reproductive and respiratory syndrome virus,PRRSV)流行毒株的变异情况,试验收集来自华东部分地区猪场的疑似猪繁殖与呼吸综合征样品41份(山东省19份,福建省22份),采用RT-PCR方法分别进行PRRSV、高致病性猪繁殖与呼吸综合征病毒(HP-PRRSV)检测。对检测出的阳性样品进行PRRSV的分离鉴定和ORF5基因测序,对测得序列进行遗传进化分析和推导氨基酸序列变异分析。结果表明:山东地区PRRSV检出率为74%,其中HP-PRRSV检出率为21%;福建地区PRRSV检出率为56%,其中HP-PRRSV检出率为42%。用Marc-145细胞从疑似猪繁殖与呼吸综合征病料中分离到16株PRRSV,其中10株为福建毒株,6株为山东毒株;测序获得的16株分离株中12株分布于美洲型的4个亚群,4株处于亚群之间的特殊进化位置。16株分离株以点突变为主,未见插入突变,糖基化位点30,44,51 aa处保守,32～35 aa处变异频繁。说明山东和福建地区流行的毒株不断变异,NADC30亚群毒株已经在山东地区出现,福建地区流行毒株仍以高致病毒株为主,但个别毒株已位于特殊进化位置。 相似文献
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1 猪繁殖与呼吸综合征持续存在的根源分析
1.1 病毒有较高的变异性
猪繁殖与呼吸综合征由猪繁殖与呼吸综合征病毒引起,该病也被称为蓝耳病,这种病毒常记为PRRSV,属于RNA病毒.PRRSV病毒变异性强,有欧洲型病毒,也有美洲型病毒,两者之间有较大的差异.对于同一类型的病毒,会有多种分离株,其相互间也有较大差异.近些年... 相似文献
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猪繁殖与呼吸综合征(PRRS),俗称猪蓝耳病,是由猪繁殖与呼吸综合征病毒(PRRSV)引起的一种严重危害养猪行业的高度接触性传染病.PRRSV可分为欧洲型和美洲型两个基因型,前者主要流行于欧洲地区,后者主要流行于美洲和亚太地区.PRRSV型间差异显著,型内各毒株变异大.分子生物学研究表明欧洲和美洲两地区的分离株存在广泛... 相似文献
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为了解山东省规模化猪场猪繁殖与呼吸障碍综合征病毒(PRRSV) NSP2变异株的感染情况,2010～2011年本研究从山东省未免猪繁殖与呼吸障碍综合征(PRRS)疫苗猪场、免疫进口PRRS弱毒苗猪场和免疫国产PRRS弱毒苗猪场选择20个临床表观健康的规模化猪场,采集830份血清,利用RT-PCR方法对其进行PRRSV NSP2变异株病原学检测.结果表明山东省规模化猪场普遍存在PRRSV NSP2变异株感染,而且临床表观健康的未免疫PRRS疫苗猪场、免疫进口PRRS弱毒苗猪场及免疫国产PRRS弱毒苗猪场中PRRSV NSP2变异株的检出率由高到低,同一猪群中存在PRRSV NSP2变异株野毒和疫苗毒. 相似文献
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为了解华东部分地区猪繁殖与呼吸综合征病毒(PRRSV)流行毒株变异情况,本研究以RT-PCR技术对山东、福建发病猪场的41份组织样品进行PRRSV检测和高致病性猪繁殖与呼吸综合征病毒(HP-PRRSV)相关毒株(HP-PRRSVLike)检测,对阳性样品进行PRRSV分离、ORF5基因测序及变异分析。结果显示,福建、山东样品的阳性率分别为56%、74%;共分离到16个美洲型毒株(福建10株、山东6株),分属于Lineage 8、Lineage 5、Lineage 3、Lineage 1四个谱系,其中以Lineage 8为主。这表明PRRSV流行毒株多样化,跨谱系毒株重组值得警惕。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献
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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献